Air valve, relief valve, and pressure signal for pneumatic tires



Aprll 17, 1951 w. A. CALDWELL 2,549,571

AIR VALVE, RELIEF VALVE, AND PRESSURE SIGNAL FOR PNEUMATIC TIRES Filed March 30, 1949 2 Sheets-Sheet 1 April 17, 1951 w. A. CALDWELL AIR VALVE, RELIEF .yALvE, AND PRESSURE SIGNAL FOR PNEUMATIC TIRES 2 Sheds-Sheet 2 Filed March 30, 1949 Patented Apr. 17, 1951 AIR VALVE, RELIEF VALVE, AND PRESSURE SIGNAL FOR PNEUMATIC TIRES William Addison Caldwell, Leesburg, Tex.

Original application May 18, 1948, Serial No. 27,776. Divided and this application March 30, 1949, Serial No. 84,438

6 Claims.

This invention relates to pneumatic tires for vehicles. It has for its object to provide certain improvements in the construction of such tires, particularly the inner tube, primarily for the purpose of protecting it against excessive pressure at the time of inflation as well as in the course of ordinary operation.

A second purpose served by the invention is to provide an audible warning signal of a dangerous increase or decrease of pressure in regard to the normal operating limit.

To accomplish the aforesaid purposes, I pro vide a new type of valve mechanism for the inner tube located exteriorly thereto and operated by a power member located within the tube and actuated by changes in the air pressure therein adapted to determine automatically the amount of air pressure that can be and should be initially injected into the tube; to release excessive pressure from the tire as a final step in the circulation of air through it, when the said valve mechanism is used conjointly with a pressure and temperature equilibrator, or automatic inflation pump; and to give timely warning by means of an audible signal of any unusual increase in pressure or loss of pressure beyond the power of the equilibrator to compensate it.

To these and other ends, my invention comprises other improvements and advantages as will be fully described in the accompanying specification, the novel features thereof being set forth in the appended claims.

This application is a division of application Serial [No. 27,776 filed May 18, 1948 and issued June 27, 1950 as Patent No. 2,512,766.I

In the drawings:

Figure l is a vertical section of an inner tube of a pneumatic tire, showing the same inflated, in which the several elements of my invention are illustrated as they appear in elevation.

Figure 2 is an enlarged vertical section of the inlet air valve and power member taken on the same sectional plane as that of Figure 1.

Figure 1 only the air chamber or inner tube Ill-of a pneumatic tire, which when inflated as shown, assumes the shape of a circular tube, which is also circular in cross section. At one point in the I tube there is fixed externally the air inlet valve ll, and the associated internally located power member l2. Oppositely disposed within the tube is a pressure and temperature equilibrator indi-' cated by the numeral [3, same being the subject of co-pending application No. 27,776. Intermediate the ends of the equilibrator, it is is connected to the tube II] by a nipple M having a valve controlled air inlet opening exteriorly of the tube. The equilibrator l3 has at its ends interior valves, which are connected by'the flexible rods l5, 16, also located within the tube, to1the flange 18 of the base of the first mentioned inlet valve.

Each of these rods carries multiple weights ifia', Ilia, which upon rotation of the wheel carrying the tire, are displaced by centrifugal force, and thus serve to actuate the equilibrator.

The specially constructed air inlet shown inr Figure 2 comprises a tubular base ll having at its interior end a flange I8 which engages the a central chamber llb which opens at its inner end into thetube 10 through a passage He. The

Figure 3 is a crosssection of the valve nipple taken on the line 33 of Figure 2.

Figure 4 is a cross section of the power member taken on the line 44-of Figure 2. V

Figure 5 (Figure 8 on the accompanying photobase l] is extended upwards by a hollow nipple 25secured by threads 25c. V I

Beyond, the threads 250 the side walls of the base llare cut away to form the arms 26 as shown The upper end of the nipple 25 extends beyond the top of the arms 26 and has a chambered pas sage, in the extremity of which is inserted 'a removable tubular screw threaded plug forming an annular valve seat 26b. 7

There is a valve stem 27 centrally located in the outer end of the nipple 25 carrying a head 28 provided with a rubber pad which is normally closed against the valve seat by a coil spring 29. The upper end of this spring engages the valve head, and its lower end engages the shoulder 26a. Extending outwardly from the center of the head 28 is a conical projection 28a removably secured to the stem 21, which being of lesser diameterthan the valve seat opening, performs the dual purpose'of securing the pad at the same time re- The outer end Ila of the stricting the opening in the valve seat 25b when the head 28 is slightly disengaged from said seat. In order that the stem 2'! may be retracted on occasion from within the tire to relieve an excessive pressure or to actuate an audible signal in case the pressure becomes subnormal, its lower end which extends into the chamber below the shoulder 26a is provided with a head Guided within the chamber Nb and between the arms 26 is a trip member 3! composed of two similar side pieces integrally connected at their outer ends by a perforated shoulder, through which the valve stem 21 projects. The trip member is slidably fastened by the head Sil to the valve stem, and the trip member is normally held in an outward inoperative position by a compression coil spring 33 located beneath it in the chamber of the base H.

The lower ends of the trip member 31 carry a transverse pin 34, and depending therefrom is a rod 35, the lower end of which extends through the passage in the flange H! of the valve stem into the air chamber of the inner tube it where it is provided with an enlargement 36 having upper and lower conical surfaces 35a, 3%, the former being located a short distance beneath the flange E8. The extremity of the rod 3-5 beyond the conical enlargement 35 is guided in a central perforation in a cross bar 3'5, and fastened to it by the head 35a.

' With further reference to the air inlet valve, it will be observed that the nipple 25 is threaded exteriorly as indicated at 33, beyond which it is reduced in diameter and again threaded exteriorly to accommodate the connection cap of the usual air pump hose, by means of which air is introduced under pressure into the inner tube ill. A rubber cap 39 is stretched over the top of the nipple 25 and is enclosed by a retaining closure 40 which engages the threads 38. In line with the axis of the valve seat 2%, both the rubber cap and its retaining closure are provided with small alined perforations 45, and in the sides of the closure 46 are round apertures iiia, The perforations are for the purpose of permitting small quantities of air to escape on occasions when the valve head 28 is partially disengaged from its seat 261), and the apertures Aim are for the purpose of allowing larger quantities of air to escape when said head has been retracted sufiiciently to disengage the projection 28a from the valve seat aperture. The large quantity of air in escaping will rupture the side walls of the cap with a loud report that will serve as an audible signal.

Associated with the air inlet nipple and in alinement therewith, within the air chamber it] of the tire is a power member comprising parts which are actuated by changes in the air pressure for retracting rod 35 to open the air inlet valve. The head piece 59 of this element has spaced upwardly'extending arms by means of which the power member is fastened to the cross bar 3?. The upper ends of these arms are normally held in engagement with the inner or bottom face of the flange [8 by the compression spring 33. In order to counterbalance the effect of centrifugal force acting on the power member during the usual rotation of the associated wheel, which would otherwise tend to overcome the tension of the spring 33, I attach to the head 58 flexible cords 52, which are trained over pulleys 53 carried on bearing members attached to the bottom of flange l8, and I attach to the free ends of these cords suitable weights 54.

Projecting downward from the head piece 56 is an annular collar 55, to which is attached a short piece of rubber tubing 56 closed at its other end by a similar head 69. This tube is compressible lengthwise only, being braced against collapsing under air pressure by compression coil springs 63, 6 5, and. a series of discs 5! formed integrally on a central stem 62, which discs also serve to adapt the tube to fold bellows-like under pressure. This longitudinally compressible member 5a is mounted in a rectangular cage composed of parallel sets of rods 55-S5, 68-65 which extend under the head and are attached thereto by a bolt 6'5. These rods extend past the head which is guided for longitudinal movement thereon, and extendacross said head at a point between the cross bar 31 and the conical enlargement 3% as indicated at 65. The normal distance between the cage members is only slightly greater than the diameter of the rod 35 which runs between their horizontal tops, but the resilient qualities of the cage members are sufficient to enable their horizontal tops to separate as the cage moves upward so that they will slide over the tapered surface 382), and thus spring over the enlargement 38, whereby, when there is a loss of air pressure from the tire, and the cage is moved in the opposite direction, it will act to retract the valve head 28 from its seat 26b.

In the construction of the power member l2,

the compressional tension of springs 53, 56 must be such as to allow the bottom 56 of the rubber member to be elevated until the top of the cage 55, 66-58 engages the bottom or" the base I! of the air inlet nipple with sufficient force to establish an equilibrium with the spring 33 at normal operating air pressure, plus a modicum sufficient to overcome said spring when the pressure is raised above normal and open the inlet valve 28, thus allowing the excess pressure to escape.

To further explain the operation of the power member [2; since after the top of the cage 6565, 56-66 has reached the bottom of the base ll of the valve nipple, the rubberelement will still be susceptible of further compression; and since the bottom end fill of the power member can not move any farther upward, the top end 55 must move downward, overcoming the opposition of the spring 33 and pulling open the inlet valve 28. And as long as this valve is held open, it will be impossible to force more air into the tire with a hand or power pump, because the compressed air will follow outwardly the piston of the pump, thereby preventing the infiow of air from the outside at atmospheric pressure.

In this connection, it should be observed that normally, the power member 12 is suspended by its upper end from the rod 35, in which position it will continue after the tire has been inflated to or beyond its normal operating pressure. But when the tire begins to lose pressure, thereby allowing the power member to expand, since its top end can not move upward, its bottom end must move downward. And when by this downward movement the top of the cage 55-455, til-661s brought in engagement with the enlargement 36 on the rod 35, the power member will no longer be suspended by its upper end, but by the top of the cage @555, 66-436, in which position it will continue until the head 35a on the rod 35 is drawn downward far enough to engage the upper or outer face of the head so, when the top or" the cage fi5-65, ES-i66 will ,slipover the enlargement 36, thus allowing the power member to regain its normal position.

The operation of my invention as a whole is as follows:

Beginning with an empty tire, the retaining closure 40 and the rubber cap 39 are removed and the air pump is connected to the neck of the nipple 25. As air is pumped into the inner tube in the usual way, the increasing pressure will compress the rubber element 56 and the springs 63, B4 of the power member l2, thereby forcing upward the lower end 60 thereof until the top of the cage 6565, 66-66 in which the power member is mounted engages the flange [8 of the nipple base. Thereafter, any further increase in pressure will cause the top of the power member l2, until now held against the nipple base or flange l8 by the spring 33, to move downward,

' thereby retracting the rod 35 and disengaging the head 28 of the air inlet valve from its seat, when air will begin to retrogress from the inner tube H3 and stop the pump from functioning. Or if the tire is filled from a tank, upon removal of the hose nozzle from the neck of the valve nipple 25, air will escape from the inner tube It until the pressure has been reduced sufficiently to allow the top of the power member [2 to regain its normal position in engagement with the flange l8 of the nipple base, when the Valve head 28 will also regain its normal position and close the valve. The same result would follow an increase of pressure in a normally inflated tire, whether caused by an equilibrator, atmospheric changes, or friction against the roadbed.

After the tire has been duly inflated to its normal operating capacity, predetermined by the power member 12 in the manner above described, and the rubber cap 39 and retaining closure 40 restored to their usual position, any loss of pressure by leakage or otherwise will cause the lower end of the power member I2 to recede from its elevated operating position until the top of the cage 6565, (EB-63 engages the enlargement 36 on the rod 35 which will then be retracted, thereby disengaging the valve head 28 from its seat, and finally opening the valve completely, whereupon, air will escape from the inner tube through the canal ll'c in the base of the inlet valve nipple in sufficient quantity to rupture the rubber cap 39, thereby producing an audible warning signal. Air will continue to escape through the nipple and the bottom of the power member I2 will continue to move downward until the' end of the rod 35 engages the top of the head 50, when the cage 65-65, 66-456 will be forced to release its hold on the enlargement 36 by springing over it, thus allowing the spring 33 as well as the top 53 of the power member and the valve head 28 to regain their normal position, thereby closing the valve to prevent the needless loss of air through the nipple after the warning signal has been sounded.

Any increase of pressure above the normal operating point, generally will but partially open the valve 28, while a loss of pressure because of a continuous leakage will invariably open the valve completely.

I claim:

1. The combination with a pneumatic tire having an air inlet stem provided with a valve seat, a spring operated valve head engaging the seat "and a release rod in said stem cooperating with said valve head and having a radially outer end extending into the tire, of a power member within the tire comprising two relatively movable heads, one of which is positioned in contact with the radially outer end of the air inlet stem, said member being capable of contracting and expanding with changes of air pressure within the tire to vary the position of its movable parts with relation to said valve stem, and means operated by the movement of said heads and cooperating with the radially outer end of the release rod for actuating it to release the valve head upon the devel opment of an excessive pressure of air in the tire, or a substantial loss of pressure therefrom.

2. The combination with a pneumatic tire having an air inlet stem provided with a valve seat, a spring operated valve head engaging the seat, a release rod in said stem cooperating with the valve head and having a radially outer end extending into the tire, and a spring holding the rod retracted which is set in accordance with a given tire pressure, of a power member-within the tire suspended on the radially outer end of the retracting rod and held by the last mentioned spring in engagement with the radially outer end of the inlet stem, said power member comprising a flexible tube, heads thereon, and resilient means normally holding them in spaced relation in accordance with a given tire pressure, means operated by one of the heads acting under such pressure for tripping engagement with the retracting rod, the other end serving upon a lessening of the pressure in the tire also to cause said means to retract the rod.

3. In combination with a radially inner tube of a pneumatic tire, an air inlet stem having a valve seat and a movable valve head, a release rod for said head projecting into the radially inner tube, and a power member within the inner tube capable of contraction and expansionunder changes in air pressure occurring within the tube, operating connections between it and said retraoting rod for disengaging the valve head from its seat, weights attached to the radially inner head of the power member by flexible cords trained over pulleys attached to the radially outer end of the inlet valve stem to counterbalance the effect of centrifugal force acting on the power member during the rotation of the wheel with which it may be associated.

4. The combination with a pneumatic tire having an air inlet stem provided with a valve seat, a valve head normally engaging with the said seat, a cap enclosing the outer end of the valve stem capable of rupture having an air vent in its top to protect it against rupture by a small quantity of air under pressure escaping from the tire through the valve stem, a retaining closure having an air vent in alinement with the one in the cap and apertures in its sides to allow the rupture .-of the cap and limit the extent of the rupture by air under pressure escaping from the inner tube through the valve stem in excess of the capacity of the air vent to discharge it, and a rod for releasing the valve head having a radially outer end projecting into the tire provided with a bulbous enlargement, of a power member within the tire suspended on the releasing rod having a head normally held thereby in engagement with the radially outer face of the base of the inlet stem, said power member also comprising a flexible tube attached to said head and connected to a second head having within it resilient means set to hold the heads spaced in accordance with a given tire pressure, means carried by the power member and operated by said pressure into actuated position with reference to the bulbous enlargement, whereby upon decreasing of said pressure the said releasing rod will be retracted to unseat the valve head.

5. The combination with a pneumatic tire having an air inlet stem provided with a valve seat, a valve head normally engaging with said seat, a sheathenclosing the outer end of the valve stem', capable of rupture having an air vent in its'top to protect it against rupture by a small quantity of air under pressure escaping from the tire through the valve stem, a retaining closure having an air vent in alinement with the one in the cap and apertures in its sides to allow the rupture of the cap and limit the extent of the same by air under pressure escaping from the inner tube through the valve stem in excess of the capacity of the air vent to discharge it, a release rod projecting from the valve head into the tire provided with a bulbous enlargement, of a power member within the tire suspended on the releas ing rod having a head normally held thereby in engagement with the radially outer end of the air ance with a given tire pressure adapting the said 5 flexible tube to fold bellows-like under the said pressure.

v6. In combination with a radially inner tube of a pneumatic tire, an air inlet step having a valve seat and a movable valve head, a conical projection extending radially inward from the valve head and fitting sliclably in the opening in the valve seat, and a release rod cooperating with the valve head and extending into the chamber of the inner tube, a power member within the tube capable of contraction and expansion under changes of air pressure occurring Within the tube, and operating connections between the power member and said rod for disengaging the valve head from its seat.

WILLIAM ADDISON CALDWELL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,303,893 Haskins et al. May 20, 1919 1,894,908 Hopkins Jan. 17, 1933 1 ,930,04l Crowley et al Oct. 10, 1933 

